It is narrated from Sayyiduna Ali (may Allah be pleased with him): I used to have a great deal of pre-seminal fluid (madhy), and I felt shy to ask the Messenger of Allah (peace and blessings be upon him) about it because of his daughter. So I told Miqdad bin al-Aswad (may Allah be pleased with him) to ask him (peace and blessings be upon him). He (peace and blessings be upon him) said: "He should wash his private part and perform ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 560
It is narrated from Sayyiduna Ali (may Allah be pleased with him): I felt shy, because of Sayyidah Fatimah (may Allah be pleased with her), to ask the Messenger of Allah (peace and blessings be upon him) about pre-seminal fluid (madhy). So I told a man, and he asked him (peace and blessings be upon him). He (peace and blessings be upon him) said: "For it there is ablution."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 561
It is narrated from Sayyiduna Miqdad bin al-Aswad (may Allah be pleased with him) that Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) told him to ask the Messenger of Allah (peace and blessings be upon him) about one of us: when pre-seminal fluid comes out of him, what is required of him? "For his daughter is married to me, and I feel shy to ask." Miqdad (may Allah be pleased with him) said: I asked him (peace and blessings be upon him), and he (peace and blessings be upon him) said: "When one of you finds that (pre-seminal fluid), let him wash his private part and perform ablution as he does for prayer."
(b) This narration is also transmitted from Sayyiduna Ibn Abbas (may Allah be pleased with them both) in connected (mawsul) form.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 562
Sayyiduna Ali (may Allah be pleased with him) says: I sent Miqdad (may Allah be pleased with him) to the Messenger of Allah (peace and blessings be upon him), and he asked him about the pre-seminal fluid that comes out of a person: what is the ruling on it? He (peace and blessings be upon him) said: "Perform ablution and sprinkle water on your private part."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 563
(a) Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says concerning semen (mani), pre-seminal fluid (madhy) and post-urinary discharge (wady): For semen there is a ritual bath (ghusl), and for pre-seminal fluid and post-urinary discharge there is ablution; (such a person) should wash his private part and perform ablution.
(b) Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: Wady comes after urinating, and for it there is ablution.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 564